Mobile cameras such as those embedded in smart phones are increasingly widely deployed. Mobile cameras are expected to acquire, record and sometimes compress and transmit images and video in various challenging lighting and weather conditions. For example, the mobile cameras may capture images or videos in low-lighting conditions or hazy conditions, which make capturing a satisfactory image challenging.
The majority of portable cameras are not specifically designed to be all-purpose and weather-proof, rendering the images and video footage unusable, or unsatisfactory, under various lighting conditions. Image and video processing and enhancement including gamma correction, de-hazing and de-blurring are well-studied areas. Although many algorithms perform well for different specific lighting impairments, they often require tedious and sometimes manual input-dependent fine-tuning of algorithm parameters.
In addition, different specific types of impairments often require different specific algorithms. Take low lighting video enhancement as an example. Although far and near infrared based systems are widely used, especially for professional grade video surveillance applications, they are usually more expensive, harder to maintain, and have a relatively shorter life-span than conventional systems. They also introduce extra, and often times considerable power consumption, making their use with mobile cameras difficult. In many consumer applications such as image and video capture and communications on smart phones, it is usually not feasible to deploy infrared systems due to such cost and power consumption issues. Other algorithms for enhancing images captured in low-light conditions have combined noise reduction, contrast enhancement, tone-mapping, histogram stretching, equalization, and gamma correction techniques. These algorithms have made tremendous progress over the years and can produce satisfactory results. However, low-lighting enhancement algorithms can be computationally complex, making their use undesirable in mobile cameras.